[Computed tomography in untreated congenital hip dislocation in adolescence]

Abstract

Untreated cases of congenital dislocation of the hip (CDH) in the adolescent age are rarely encountered in the western world but are not uncommon in our clinical practice. The pathoanatomy has not been well studied. Previously poor results of operative treatment are partially related to this lack of understanding of the true pathoanatomy and the failure to select the appropriate modality of treatment. Computed tomography (CT) has the capability to show the three-dimensional structure and was used in this study. From September 1985 to July 1988, we had 15 patients (18 dislocated hips) for CT study. Their ages ranged from 8 years 6 months to 22 years 5 months. The patients were divided into 4 types according to the position of dislocation, formation of pseudojoint and size of the true acetabulum: (1) high dislocation without pseudojoint formation; (2) high dislocation with pseudojoint formation; (3) low dislocation with pseudojoint formation; and (4) wide acetabulum. By measuring the diameter of the true acetabulum and femoral head, and the anteversion of the true acetabulum and proximal femur, we had the following results: (1) the size of the acetabulum and femoral head in dislocated hips were smaller than the normal side; (2) most of the acetabula in the dislocated hips were still large enough to accommodate the corresponding femoral heads, even up to the age of 22 years; and (3) the degree of anteversion was similar between the acetabula in normal and dislocated hips, but was more prominent in the proximal femur of a dislocated hip than the normal side.(ABSTRACT TRUNCATED AT 250 WORDS)